Sunshade device with a buffer to smoothen retraction of a screen

ABSTRACT

In a sunshade device, a roller is journalled in an elongated housing and has a screen wound therearound. The roller is biased to rotate in a screen-winding direction for winding the screen thereon. A drive gear is fixed to the roller. A threaded rod parallel to the roller is fixed in the housing, and has a follower gear sleeved threadedly thereon. The follower gear is formed with grooves arranged around the rod axis and meshing with the drive gear. Each groove has a groove bottom, and first and second groove ends formed respectively at first and second end portions of the follower gear. The groove bottom at the first groove end is displaced from the rod axis by a distance smaller than that of the groove bottom at the second groove end.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a sunshade device, more particularly to a sunshade device provided with a buffer which can decelerate and smoothen retraction of a screen.

[0003] 2. Description of the Related Art

[0004] Referring to FIGS. 1 and 2, a conventional sunshade device 1 for an automobile is shown to include a tubular roller 12 received in an elongated housing 10 which is mounted fixedly in the interior of the automobile (not shown), and a screen 16 wound around the roller 12 and having one end secured to the roller 12 and an opposite distal end extending out of the housing 10 via an elongated slit 101 formed in the housing 10. A mounting axle 151 has a fixed end 153 fixed to one end of the housing 10, and an opposite distal end 154 extending axially into the roller 12. A coiled torsion spring 152 is received in the roller 12, and is sleeved on the mounting axle 151. The torsion spring 152 has one end 156 hooked at the distal end 154 of the mounting axle 154, and an opposite end 155 hooked at an end plug 13 that is secured to one end of the roller 12. The torsion spring 152 thus applies a biasing force to bias the roller 12 to rotate in a predetermined screen-winding direction for winding the screen 16 thereon. A hook member 17 is provided in the interior of the automobile to permit hanging of an end strip 161 on the distal end of the screen 16 thereon so as to retain the screen 16 at a stretched position when the end strip 161 is pulled away from housing 10 for unwinding the screen 16 from the roller 12 against biasing action of the torsion spring 152.

[0005] In use, when it is desired to retract the screen 16, the end strip 161 is simply removed from the hook member 17 and is released. Due to the biasing action of the torsion spring 152, the screen 16 is then retracted rapidly into the housing 10 for winding on the roller 12 until the end strip 161 abuts against the housing 10 at the periphery of the slit 101. It is noted that rapid retraction of the screen 16 results in collision between the end strip 161 and the housing 10, which generates undesired shock and noise.

SUMMARY OF THE INVENTION

[0006] Therefore, the object of the present invention is to provide a sunshade device with a buffer to decelerate and smoothen retraction of a screen.

[0007] Accordingly, the sunshade device of the present invention includes an elongated housing with a slit, a roller mounted rotatably in the housing and having a roller axis, and a screen wound around the roller and having a connecting end secured to the roller, and a distal end opposite to the connecting end and extending out of the housing via the slit. A biasing unit biases the roller to rotate in a screen-winding direction for winding the screen thereon so as to move the screen to a retracted position, in which the distal end of the screen is disposed adjacent to the housing. The roller is further rotatable in a screen-unwinding direction opposite to the screen-winding direction against biasing action of the biasing unit for unwinding the screen therefrom so as to permit movement of the screen to a stretched position, in which the distal end of the screen is moved away from the housing. A drive gear is fixed to the roller, and has an outer surface formed with a plurality of drive teeth, which are arranged around the roller axis. A threaded rod is mounted fixedly in the housing, is disposed parallel to the roller, and has a rod axis. A follower gear is sleeved threadedly on the threaded rod, and has first and second end portions opposite to each other along the rod axis. The follower gear further has an outer surface formed with a series of meshing grooves that are arranged around the rod axis and that mesh with the drive teeth on the drive gear. Each of the meshing grooves extends from the first end portion to the second end portion of the follower gear, and has a groove bottom extending along the length of a respective one of the meshing grooves, a first groove end formed at the first end portion of the follower gear, and a second groove end opposite to the first groove end and formed at the second end portion of the follower gear. The groove bottom at the first groove end of each of the meshing grooves is displaced from the rod axis by a first distance. The groove bottom at the second groove end of each of the meshing grooves is displaced from the rod axis by a second distance. The first distance is smaller than the second distance. Rotation of the roller in the screen-winding direction results in corresponding rotation of the follower gear to cause linear movement of the follower gear along the threaded rod in a first direction for moving the second end portion of the follower gear toward the drive gear. Rotation of the roller in the screen-unwinding direction results in corresponding rotation of the follower gear to cause linear movement of the follower gear along the threaded rod in a second direction opposite to the first direction for moving the second end portion of the follower gear away from the drive gear. The drive teeth on the drive gear are in frictional contact with the groove bottoms of the meshing grooves at the second groove ends when the second end portion of the follower gear is moved to be disposed proximate to the drive gear, thereby generating a resistance force to retard rotation of the drive gear and the roller in the screen-winding direction.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:

[0009]FIG. 1 is a perspective view showing a conventional sunshade device;

[0010]FIG. 2 is a fragmentary partly-sectioned view of the sunshade device of FIG. 1;

[0011]FIG. 3 is a partly-sectioned view of a preferred embodiment of a sunshade device of the present invention;

[0012]FIG. 4 is a fragmentary partly-sectioned view of the preferred embodiment, showing a drive gear engaging a narrower first end portion of a follower gear;

[0013]FIG. 5 is a cross-sectional view showing the engagement between the drive gear and the follower gear of FIG. 4;

[0014]FIG. 6 is another fragmentary partly-sectioned view of the preferred embodiment, showing the drive gear engaging a wider second end portion of the follower gear; and

[0015]FIG. 7 is a cross-sectional view showing the engagement between the drive gear and the follower gear of FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0016] Referring to FIGS. 3 and 4, in the preferred embodiment of the sunshade device according to the present invention, a housing 30 includes first and second mounting seats 2, 3 disposed at two opposite ends, and an intermediate housing part 35 between the first and second mounting seats 2, 3. The first mounting seat 2 has a base wall 21 adapted to be fixed to the interior of an automobile, such as the platform adjacent to an automobile rear window, by means of an adhesive tape attached to the bottom side of the base wall 21, or by means of screw fasteners. The first mounting seat 2 further has parallel first and second mounting walls 22, 23 extending upwardly from the base wall 21, and a curved confining wall 24 extending upwardly from an outer end of the base wall 21. The confining wall 24 has an inner side formed with a mounting block 25 that is formed with a circular hole 251. The second mounting seat 3 similarly includes a base wall 31 adapted to be fixed to the interior of an automobile by means of an adhesive tape or screw fasteners, and a curved confining wall 32 with an inner side formed with a mounting block 33. The intermediate housing part 35 extends between the first and second mounting seats 2, 3, and is formed with a longitudinally extending slit 351.

[0017] A tubular roller 4 has a roller axis (L), a first end 411 mounted on the first mounting seat 2, and a second end 412 opposite to the first end 411 along the roller axis (L). A mounting axle 44 extends along the roller axis (L), and has a fixed end 442 fixed to the mounting block 33 on the second mounting seat 3, and an opposite distal end 441 extending into the roller 4 through the second end 412 of the roller 4. The second end 412 of the roller 4 is provided fixedly with an end plug 43 which is sleeved rotatably on the mounting axle 44 for mounting the roller 4 rotatably on the second mounting seat 3. The first end 411 of the roller 4 has a drive gear 42 fixed thereto. The drive gear 42 is formed from plastic material, and includes a cylindrical portion 21 press-fitted to and extending into the first end 411 of the roller 4, and a teeth forming portion 422 disposed externally of the roller 4 and formed with a plurality of drive teeth 424 that are arranged around the roller axis (L). The drive gear 42 has a pin projection 423 which extends along the roller axis (L) and which is inserted rotatably into the circular hole 251 in the mounting block 25 of the first mounting seat 2 for mounting the first end 411 of the roller 4 rotatably on the first mounting seat 2.

[0018] A flexible screen 5 is wound around the roller 4, and has a connecting end 51 secured to the roller 4, and a distal end 52 opposite to the connecting end 51 and extending out of the housing 30 via the slit 351. The distal end 52 is provided with an elongated strip 521, which is formed with a hanger 53 thereon. A biasing unit, in the form of a coiled torsion spring 45, is received in the roller 4 and is disposed around the mounting axle 44. The torsion spring 45 has a first end 451 engaging the distal end 441 of the mounting axle 44, and an opposite second end 452 connected to the roller 4 via engagement with the end plug 43 on the second end 412 of the roller 4. The torsion spring 45 thus provides a biasing force to bias the roller 4 to rotate in a predetermined screen-winding direction for winding the screen 5 on the roller 4 so as to move the screen 5 to a retracted position, in which the screen 5 is substantially retracted into the housing 30 and in which the strip 521 on the distal end 52 of the screen 5 is disposed adjacent to the housing 30 and abuts against the housing 30 at the periphery of the slit 351. The roller 4 is further rotatable in a screen-unwinding direction opposite to the screen-winding direction when the strip 521 is pulled away from the housing 30 for unwinding the screen 5 from the roller 4 against the biasing action of the torsion spring 45 so as to permit movement of the screen 5 to a stretched position, in which the distal end 52 of the screen 5 is moved away from the housing 30 and in which the screen 5 is substantially stretched from the housing 30. A hook member 6 is provided in the interior of the automobile to permit hooking of the hanger 53 thereon for retaining the screen 5 at the stretched position.

[0019] Referring to FIGS. 4 and 5, in the first mounting seat 2, a threaded rod 71 is mounted fixedly on and extends between the first and second mounting walls 22, 23 in a direction parallel to the roller axis (L).The threaded rod 71 is formed with an external screw thread 711 along the length thereof. A follower gear 73 formed of a resilient material, such as rubber, is sleeved threadedly on the threaded rod 71, and is disposed adjacent to the drive gear 42. The follower gear 73 has an axial hole 733 that permits extension of the threaded rod 71 therethrough and that is formed with an internal screw thread for engaging threadedly the external screw thread 711 on the threaded rod 71. The follower gear 73 has a truncated-cone shape, and has cross-sections which gradually diverge from a first end portion 731 of the follower gear 73 toward a second end portion 732 opposite to the first end portion 731 along a rod axis (R) of the threaded rod 71. The follower gear 73 has an outer surface extending around the rod axis (R) and formed with a series of elongated meshing grooves 735 that mesh with the drive teeth 424 on the drive gear 42. Each of the meshing grooves 735 extends from the first end portion 731 to the second end portion 732 of the follower gear 73, and has a first groove end 737 formed at the first end portion 731, an opposite second groove end 738 formed at the second end portion 732, and a groove bottom 736 extending along the length of the respective meshing groove 735. The groove bottom 736 at the first groove end 737 of each of the meshing grooves 735 is displaced from the rod axis (R) by a first distance. The groove bottom 736 at the second groove end 738 of each of the meshing grooves 735 is displaced from the rod axis (R) by a second distance. Since the follower gear 73 has a truncated-cone shape, the first distance is smaller than the second distance.

[0020] Referring to FIGS. 6 and 7, since the drive gear 42 meshes with the follower gear 73, rotation of the roller 4 results in corresponding rotation of the follower gear 73 on the threaded rod 71. When the roller 4 is rotated in the screen-winding direction for winding the screen 5 thereon, the follower gear 73 is rotated relative to the threaded rod 71, which is fixed, to result in linear movement of the follower gear 73 along the rod axis (R) in a first direction, in which the wider second end portion 732 of the follower gear 73 is moved toward the drive gear 42. When the screen 5 is moved proximate to the retracted position, the drive teeth 424 on the drive gear 42 are disposed proximate to the second groove ends 738 of the meshing grooves 735, where tips 425 of the drive teeth 424 are in frictional contact with the groove bottoms 736 at the second groove ends 738, thereby generating a resistance force to retard rotation of the drive gear 42 and the roller 4 in the screen-winding direction. Since the cross-sections of the follower gear 73 increase gradually from the first end portion 731 to the second end portion 732, the tips 425 gradually approach the groove bottoms 736, and the resistance force increases gradually during rotation of the roller 4 in the screen-winding direction.

[0021] Referring to FIGS. 4 and 5, on the other hand, when the roller 4 is rotated in the screen-unwinding direction for unwinding the screen 5 therefrom, the follower gear 73 is rotated relative to the fixed threaded rod 71 to result in linear movement of the follower gear 73 along the rod axis (R) in a second direction opposite to the first direction, in which the second end portion 732 of the follower gear 73 is moved away from the drive gear 42. As such, the resistance force is reduced gradually. When the screen 5 is moved proximate to the stretched position, the drive teeth 424 on the drive gear 42 are disposed proximate to the first groove ends 737 of the meshing grooves 735, and the tips 425 of the drive teeth 424 are spaced-apart from the groove bottoms 736 to prevent the follower gear 73 from hindering rotation of the drive gear 42, and thus the roller 4, in the screen-unwinding direction.

[0022] The drive gear 42, the follower gear 73, and the threaded rod 71 thus constitute a buffer to decelerate and smoothen retraction of the screen 5. As such, noise and shock that occur during the retracting operation of the conventional sunshade device can be obviated.

[0023] While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements. 

I claim:
 1. A sunshade device comprising: an elongated housing formed with a slit; a roller mounted rotatably in said housing and having a roller axis; a screen wound around said roller and having a connecting end secured to said roller, and a distal end opposite to said connecting end and extending out of said housing via said slit; a biasing unit for biasing said roller to rotate in a screen-winding direction for winding said screen thereon so as to move said screen to a retracted position, in which said distal end of said screen is disposed adjacent to said housing, said roller being further rotatable in a screen-unwinding direction opposite to the screen-winding direction against biasing action of said biasing unit for unwinding said screen therefrom so as to permit movement of said screen to a stretched position, in which said distal end of said screen is moved away from said housing; a drive gear fixed to said roller, said drive gear having an outer surface formed with a plurality of drive teeth which are arranged around said roller axis; a threaded rod mounted fixedly in said housing, disposed parallel to said roller, and having a rod axis; and a follower gear sleeved threadedly on said threaded rod, said follower gear having first and second end portions opposite to each other along said rod axis, said follower gear further having an outer surface formed with a series of meshing grooves that are arranged around said rod axis and that mesh with said drive teeth on said drive gear, each of said meshing grooves extending from said first end portion to said second end portion of said follower gear, and having a groove bottom extending along length of a respective one of said meshing grooves, a first groove end formed at said first end portion of said follower gear, and a second groove end opposite to said first groove end and formed at said second end portion of said follower gear, said groove bottom at said first groove end of each of said meshing grooves being displaced from said rod axis by a first distance, said groove bottom at said second groove end of each of said meshing grooves being displaced from said rod axis by a second distance, said first distance being smaller than said second distance, rotation of said roller in the screen-winding direction resulting in corresponding rotation of said follower gear to cause linear movement of said follower gear along said threaded rod in a first direction for moving said second end portion of said follower gear toward said drive gear, rotation of said roller in the screen-unwinding direction resulting in corresponding rotation of said follower gear to cause linear movement of said follower gear along said threaded rod in a second direction opposite to the first direction for moving said second end portion of said follower gear away from said drive gear, said drive teeth on said drive gear being in frictional contact with said groove bottoms of said meshing grooves at said second groove ends when said second end portion of said follower gear is moved to be disposed proximate to said drive gear, thereby generating a resistance force to retard rotation of said drive gear and said roller in the screen-winding direction.
 2. The sunshade device as claimed in claim 1, wherein said follower gear has a truncated-cone shape and has cross-sections which gradually diverge from said first end portion to said second end portion of said follower gear.
 3. The sunshade device as claimed in claim 1, further comprising a mounting axle extending co-axially into said roller and having one end extending out of said roller and fixed to said housing, said biasing unit including a coiled torsion spring received in said roller and sleeved on said mounting axle, said biasing unit having a first end engaging said mounting axle, and a second end opposite to said first end and connected to said roller so as to provide a biasing force for biasing said roller to rotate in the screen-winding direction.
 4. The sunshade device as claimed in claim 1, further comprising a hook member for engaging said distal end of said screen so as to retain said screen at the stretched position. 